Inside Social Games has released the top 25 Facebook games for January and -- to no surprise -- Zynga's new darling CityVille has gone straight to the top of the charts, overtaking FarmVille, which until recently, seemed darn near impossible. The real question is how long CityVille will stay at the top or if this number is inflated due to extra promotion and the 'new'ness of it all.

Other newcomers to January's Top 25 list include PopCap's Zuma Blitz, which is a timed version of the classic PC game,and CrowdStar's uber girly game, It Girl, which grew 1.2 million last month.

A few other things to point out in this list:

- CityVille gained 80 million users in one month. Wow. It's surprising to see how a city-building game, which isn't drastically different from the many other city-building games out there, gained that much traction. It's a true testament to the power of Zynga's cross-promotion (and it also might be a sign that Zynga's learning how to make more compelling games).;

- FarmVille has been losing players for monthy (roughly 30 million so far), but in December, managed to gain 4 million players One would assume that's due to a combination of all of the special events in the game for the holiday season, the return of game notifications on Facebook and a cross-promotional synergy among all of Zynga's games, many of which were also up last month (with exception of Mafia Wars).